Slurry Erosive Wear Behavior of Hot Extruded Al6061-Si3N4 Composite

Silicon nitride possess excellent hot hardness and wear resistance coupled with very good corrosion resistance. Hence, in recent years, silicon nitride has been a serious contender as a reinforcement to develop light weight metal matrix composites for several technological applications. Al6061 is most popular matrix alloy as it possess excellent formability and in particular the quality of extrudates of Al6061 is quite high and are the most preferred in space and naval applications especially for support structures and torpedoes blades respectively. Improved corrosion and slurry erosion resistance on use of silicon nitride in nickel and aluminum alloy matrices have been reported by several researchers. In the light of the above, this paper focuses on development of Al6061- 6wt% Si3N4 by stir casting the most economical and popular route followed by hot extrusion. Hot extrusion was carried out using 200T hydraulic press at extrusion ratio of 1:10 at a temperature of 550 degrees C. Slurry erosion tests were carried out using 3.5% NaCl solution containing silica sand particles of size 312 pm at different rotational speeds varying between 300 rpm and 1200 rpm. The sand concentration was varied from 10 g/l to 40 g/l. Under identical test conditions, hot extruded Al6061- 6wt% Si3N4 composite do possess better slurry erosion resistance when compared with matrix alloy. The mechanism involved in the material removal process during slurry erosion process will also be discussed.